A turbine stator vane with a cooling circuit that improves the cooling effectiveness of the airfoil as well as collects any dirt particles before passing the clean cooling air through the cooling circuit. The airfoil includes a 3-pass aft flowing serpentine circuit with a first leg located along the airfoil leading edge and connected to a showerhead arrangement for film cooling discharge. A cooling air supply channel is located between the first leg and the second leg of the serpentine flow circuit, and the cooling supply channel includes ribs arranged to produce a vortex flow within the cooling air that collects the dirt particles within a center of the vortex flow and deposits the dirt particles at the bottom of the channel. The vortex flow cooling air flows through impingement holes to produce impingement cooling on the backside wall of the leading edge with clean cooling air. The vortex flow pattern produces higher flow velocities at the outer periphery of the vortex which produces a higher impingement jet velocity of the cooling air to improve convection and impingement cooling capability.